The basic use method of hash in Ruby _ruby special topic

A collection of hashing-value pairs, similar to this: "Employee" => "salary". It is similar to an array, except that the index is the type of any object that passes through any key, not an integer index.

Sequential traversal of a hashing or value may appear arbitrary, generally not in the insertion order. If the hash value of the key being accessed does not exist, the method returns nil.
To create a hash:

Using arrays, there are various ways to create hash values. You can create an empty hash of the new class method:

months = Hash.new

You can also use new to create a hash, which is a default value, otherwise it is simply nil:

Copy Code code as follows:

months = Hash.new ("month")

Or

months = hash.new "Month"

When accessing any of the hashing, there is a default value, and if the key or value does not exist, accessing the hash table will return the default value:

#!/usr/bin/ruby

months = hash.new ("month")

puts "#{months[0]}" puts
"#{months[72]}"

This will produce the following results:

Month
month

#!/usr/bin/ruby

H = hash["A" =>, "B" => "puts" #{h['

a ']} "
puts" #{h[' B ']} "

This will produce the following results:

200

You can use any Ruby object as a key or value, or even an array, so the following example is a valid

[1, "=>"] "January"

Hashing the built-in method:

We need to have a hash object instance call hashing method. As we have seen, the following is the way of the hash object to create an instance:

Hash[[key =>|, value]*] or

hash.new [or] hash.new (obj) [or]

hash.new {|hash, key| block}

This returns a new hash value with the given object fill. Now using the created object, we can call any available instance methods. For example:

#!/usr/bin/ruby

$, = ","
months = hash.new ("month")

months = {"1" => "January", "2" => "February"}

keys = Months.keys

puts "#{keys}"

This will produce the following results:

2, 1